Lifting jack



A. AND H. E. SHRIEVES.

LIFTING JACK.

. APPLICATION FILED JUNE 4. 1920.

Patented July 4, 1922.

ALBERT SHRIEVES AND HENRY EDWIN SHRIEVES, 0F SUTTON COLDFIELD, ENGLAND.

LIFTING JACK.

arten.

Specification of Letters Patent. v

Patented July 4., 1922.

Application filed June 4, 1920. Serial No. 386,422.

T 0 all whomit may concern:

Be it known that we, ALBERT SHRIEVES and HENRY EDWIN SHmnvns, subjectsof the King of Great Britain, residing at Kings Chambers, The Parade,Sutton Coldfield, in the county of Warwick, England have inventedcertain new and useful Tmprovements in Lifting Jacks; and we do herebydeclare the following to be a full, clear, and exact description of thesame.

This invention relates to lifting jacks and has for its object toprovide a simplified and improved construction of such devices.

A. lifting jack constructed in accordance with the present inventioncomprises a base with which is associated a. guide member in whichslides the lifting pillar, ratchet teeth on the pillar, a pivotedoperating lever carrying a lifting pawl adapted to engage with saidteeth so as to be capable of lifting the pillar in its guide with a stepby step movement, and a retaining pawl also adapted to engage with saidteeth in such manner as to prevent return movement of the pillar.

Both the pawl carried by the operating lever and the retaining pawl arepreferably acted upon by a spring tending normally to press them intoengagement with the teeth upon the pillar. and preferably a device suchas a cam is provided which may be operated to allow both of said pawlsto disengage from the teeth upon the pillar so that the latter may bemoved into its lowest position.

Referring to the drawings Figure 1 is a perspective View showing the camin the position in which operation of the lever will raise the pillar.

Figure 2 is a longitudinal section with the cam in the position shown inFigure 1.

Figure 3 is a view similar to Figure 2 but with the cam in the positionin which operation of thelever will lower the pillar.

Figure 4 is a perspective view of the cam removed.

In the construction as shown on the drawings the base member may be madeas a casting and may include a base proper 1 and a guidemember 2extending vertically therefrom. This guide member may form part of astandard which may be made integral with. the base and the standard mayinclude a second upright member 3 connected to the guide member bysuitable horizontal webs 4.

The lifting pillar may consist of a member 5 of rectangular or any othersuitable cross section adapted to slide in the guide member. The liftingpillar may be prov ded with longitudinal slots 6 in opposite sidesadapted to be entered by projections 7 in the guiding member. One sideof the lifting pillar is provided with ratchet teeth 8 and the upper endof the lifting pillar may be provided with a pivot upon which isrotatably mounted a curved member 9 adapted to suit 'the axle or thelike of a vehicle.

The operating lever 10 may be pivoted to the standard adjacent thelifting pillar. One end of the operating lever is preferably forked andthe other end may terminate in a socket 11 into which may be placed abar or rod. Pivotally mounted to the forked end of the operating leveris a pawl 12, the one end of which engages with ratchet teeth upon thelifting pillar and the other end of which, upon the other side of thepivot 13 may be provided with an eye 14.

The retaining pawl 15 may be arranged below the operating lever and maybe pivoted to the standard. This retaining pawl has one end adapted toengage with the teeth upon the lifting pillar and its other end, uponthe other side of the pivot 16 may also be provided with an eye 17.

The eye upon the pawl carried by the operating lever and the eye uponthe retaining pawl may be connected together by a link 18 consisting ofa length of wire or rod. This link between the two eyes is connected tothe free end of a leaf spring 19 which is attached to the standard. Thearrangement is such that the tendency of the leaf spring is to pressboth pawls into engagement with the teeth on the lifting pillar.

Between the leaf spring and an adjacent part of the standard ispreferably disposed a cam like member 20 which can be operated by ahandle 21 working between two stops 22 upon the standard. This cam likemember is so constructed that when in one position it forces the springinto a position in which spring pressure is transmitted to the two pawlsto keep them in engagement with the teeth upon the lifting pillar, butwhen the cam is in the other position the spring acts upon the link insuch a manner as to move the two pawls upon their pivots to bring theiroperative ends out of engagement with the teeth upon the lifting pillar.

The two pawls are preferably arranged so that the retaining pawl engageswith a fresh tooth each time that the pawl carried by the operatinglever reaches the end of a lifting stroke. 7

In operation the lifting jack is arranged with the lifting pillarbeneath the article it is desired to raise and a rod or bar is insertedin the socket end of the operating lever. The operating lever is thenworked to and fro on its pivot sothat the lifting pillar is raised toothby tooth. During the lifting movement the retaining pawl serves toprevent return movement of the lifting pillar. Then the jack is nolonger required the lifting pillar can be returned to its lowestposition by operating the cam, which may have a cranked handle, so as topermit both pawls to move away from the teeth upon the lifting pillar.When the cam is operated for the release, the pawl 15 is moved clear ofthe rack but if the jack is supporting a weight the pawl 12 will be keptin engagement with the teeth of the rack. The handle is then operated tolower the rack thus bringing its free end 23 into engagement with theupper part of the pawl 15 and again forcing said pawl into engagementwith the rack but taking the next tooth to the one it took before.Simultaneously the spring 19 causes the upper pawl 12 to move clear ofthe teeth.

The handle is then lowered until the pawl 12 engages the next tooth andpawl 15 again leaves the rack. This operation is repeated to give alowering step by step motion to the pillar.

Both in the lifting and lowering operations the pawl 12 may be guidedinto and out of engagement with the teeth of the ratchet rack by the endof a set screw 24. This set screw may also be used for locking the aawl12 in engagement with the rack.

W hat we claim then i In a lifting jack, a frame, a rack verti 'callymovable therein, a lever pivotally mounted in the frame, a pawl forengaging the rack and pivotally connected to said lever, a second pawlbelow the lever, for engaging the rack, means coacting with said leverto operate said second pawl, and an adjustable abutment member mountedin the frame and arranged for engagement with and disengagement from thefirst named pawl, to cause the said pawl to engage the rack earlier inthe operative movement or to take up wear in the parts, and to alsoenable the jack to be locked in any position.

In witness whereof we afiix our signatures.

ALBERT SHBIEVES. HENRY EDWIN snmnvns.

